Pavement or roadway.



UNTTED STATES PATENT OEEICE.

FREDERICK J. WARREN, OF NEWTON, WASSACHUSETTQ.

PAVENI ENT OR ROADWAY..

forming of Letters Patent No. 675,430, dated J une 4, 1901.

Application tiled January 9. 1901. Serial Noa 42,626. (No model.)

To alt whom t may conceive;

Be itknown that I, FREDERICK J. WARREN, a citizen of the United States,residing` at Newton, in the county of Middlesex and State oflliassaehusetts, have invented a new and useful Improvement in Pavementsor Roadways, of which the following is a full, clear, and exactdescription, reference being had to the accompanying drawings, forming`a part4 of this specification, in explaining its nature.

The invention relates to a pavement or roadway having a foundation layerof stone such as is used in ordinary Macadam or Telford roads or acombination of the two, and upon which is arranged one or more layers ofsmaller stone coated or partly coated with coal-tar, coal-tar pitch,asphalt, or a mixture of them or other equivalent bituminous material,and which is thoroughly rolled preparatory to receiving a finishing orbinding layer consisting of crushed or broken stone or gravel mixed withfine crushed screenings, sand, gravel, or other equivalent earthyn1atter in such proportion that the fine particles of stone, sand, orgravel in said surface or binder layer will readily enter and till thelarge voids and spaces in and between the larger stone and gravel, thesaid last-named ingredients beingl iirst thoroughly mixed with orwithout heating and preferably by suitable machinery with coal-tar,coal-tar pitch, asphalt, ora mixture of them or equivalent bituminousmaterial, thoroughly incorporated with them and in such proportions asto form a solid impervious bituminous Wearing surface or binder unitedby pressure and by permeation with the intermediate course or layer ofstone upon which it' is erected, and with the voids and spaces thereinthe under surface of the said su rfacing or binder layer knits, Thissurfacing or binding layer is preferably of uniform thickness throughoutand consolidated by means of pressure or a heavy steam-roller.

The invention will now be described in connection with the drawings,wherein- Figure 1 is a view in vertical section of a pavement having thefeatures of my invention. Fig. 2 is a detail view in section, enlarged,of Fig. l. Fig. 3 is a detail view in section, enlarged, of amodification.

The foundation layer of stone A may be of .the Macadam order or theTelford arrangement or a combination of the two, and it is laid in anyusual way. Upon it is arranged the layer B of smaller stone, whichpreferably are coated or partly coated with coal-tar, coaltar pitch,asphalt, or a mixture of them or other equivalent bituminous material.The stones composing this layer will vary in size from two inches indiameter to six inches in diameter,

Vand the layer is thoroughly rolled into the foundation layer and willwhen completed furnish a surface which is coarse and a constituencywhich is more or less cellular in character. Upon and into this preparedsurface is then thoroughly rolled a heavy layer of speciallypreparedingredients which have reference to their packing and binding characterwith regard to each other and also with respect to the character of thesurface which is to receive it and of the voids, cells, or spaces in it.This layer is a binding or surfacing layer, and it is constituted tounite with the rough surface of its supporting-layer by entering thespaces, channels, and voids between the stones thereof to a veryconsiderable extent and so as to fill them. It is further constituted tomake a continuous, homogeneous, solid layer of its own composition abovethe line of union with the layer below and to pr0 vide a hard, firm,solid, waterproof, tenacious, non-friable covering for the foundation,and the surface of which may serve as the finished surface 0f thepavement or may act to receive a finishing-surface of a somewhatdifferent character. It is obvious from what I have said that this layermust be very carefully prepared, as upon it hinges the eect-4 iveness ofthe invention. It is composed of a mixture of relatively coarseparticles onehalf inch to three inches in diameter, intermediateparticles one-tenth inch to one-half inch in diameter, and :fineparticles (an impalpable powder) to one-tenth inch in diameter, suitablyproportioned, graded, and thor oughly mixed, either hot or cold, with anincorporated composition of coaltar, coal-tar. pitch, asphalt, or otherequivalent bituminous material or a combination of them. The ingredientsare such as will pass through screens having a three-inch mesh, ahalf-inch mesh, one-tenth of an inch mesh, 0ne-fortieth of au inch mesh,one-eightieth of an IOO inch mesh, and one two-hundredth of an inchmesh. Of the ingredients passing through a screen of threeinch mesh andremaining upon a screen of one-half-inch mesh I take aboutseventyparts.Of theingredientspassing through a screen of a one-half-inch mesh .andremaining upon a screen of one-tenthinch mesh I take twenty parts andthe same as to screens of one-tenth-inch mesh and onefortieth-ineh mesh.I take four parts of screens of oue-fortiethinch mesh andoneeightieth-inch mesh, three parts of screens of one-eightieth-inchmesh and one two-hundredth-inch mesh, and of material passing through ascreen of one-two-hundredth-inch mesh one part.weight,oftheseingredients,in theproportions above stated, there areadded about six parts of the coal-tar, coal-tar pitch, asphalt, or amixture of them or other equivalent bituminous material, which,preferably, has been heated in a separate vessel, and the ingredientsand the bituminous material are intimately intermingled. The percentageof the bituminous material to the aggregate of ingredients may be variedand to obtain the best results must be varied as the shape and size ofthe larger particles in the aggregate vary and also with the degree ofpurity of the bituminous material used.

The surface of the roadway may or may not be covered with a thin coatingof bituminous mixture of sand, gravel, screenings, or'gravel mixed withcoaltar or other equivalentP material.

, 'Referring again to the drawings, C reprey sents the layer of preparedingredients, and

E,'l `ig. 3, the thin finishing-coating above referred to.`

yIamawarethat tarred Macadam pavements or roadways have been used inwhich the several courses of stone are coated with ltar in an effort tohold the top course of tarred stone about two inches in size in positionby spreading over and rolling into the surface a ,fine mixture of sandand tar; butthis only partially fills the voids in the top course ofstone, leaving voids in the lower portion of this course of stone, sothat under traffic the stones become displaced and lose the essentialsolidity desired. I am also aware that asphalt-pavement mixtures havebeen made To one hundred parts, by

are then filled with coal-tar, coal-tar pitch, asphalt, or otherequivalent bituminous ma` terial, forming a solid bituminous concreteWearing-surface and which I prefer to lay from'one to three inches ormore in thickness. By using in the concrete coarse particles of stone orgravel from about one-half inch to about three inches in diameter andmedium particles of the same from one-tenth inch to one-half inch indiameter my invention provides a composition having fewer voids, andtherefore requiring less of the` bituminous material to make a solidconcrete, than is now used in surface mixture for asphalt or otherbituminous pavements.

The concrete mixture which I have described may also be used as anintermediate or binder course between hydraulic-cement, concrete,bituminous-concrete, or brokenstone foundation and the wearing-surfaceof an ordinary asphalt pavement and is an improvement on binder coursespreviously used, for the reason that it forms a more solid andimpervious binder course.

Having thus fully described my invention, I claim and desire to secureby Letters Patent of the United Statesl. In a tar, asphalt orbituminous, Macadam roadway or pavement, a wearing surface or binder coursecomposed of coarse particles one-half inch to three inches in diameter,intermediate particles one-tenth inch to ouehalf inch in diameter andfine particles .(an impalpable powder) to one-tenth inch in diamcterin.about the proportions named and intimately combined either hot orcold with coal-tar,coaltarpitch,asphalt orother equivalent bituminousmaterial and rolled upon a prepared foundation to form a union therewithand a solid, watertigl1t, bituminous consistency, substantially as setforth.

2. The combination in a pavement or roadway of a foundation layer oflarge stone, a suitable layer of small stone coated with bituminousmaterial and rolled to a union with the larger stone and a rough surfaceand a layer of composition comprising coarse particles one-half inch tothree inches in diameter, intermediate particles one-tenth inch toone-half inch in diameter and fine particles (an impalpable powder) toone-tenth inch in diameter in about the proportions indicated, mixed hotor cold with coal-tar, coal-tar pitch, asphalt or other equivalentbituminous material spread upon and rolled into the prepared foundationmaking union with the surface thereof and iling the voids and spacestherein whereby it is knitted thereto and whereby also a solid,water-tight bituminous surfacing is provided.

FREDERICK J. VARREN.

Witnesses:

F. F. RAYMOND, 2d, J. IWI. DoLAN.

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